Upon its entry into an S3 state of Advanced Configuration and Power Interface (ACPI) (hereinafter referred to as ACPI S3), that is, a “suspend to memory” state, a conventional computer motherboard begins to operate in a standby power-saving mode, but some of the chips of the conventional computer motherboard, such as a main memory, a south bridge chip, a north bridge chip, a super input output (SIO) chip, and a memory controller, continue to consume power, and even the CPU cannot stop consuming power, and in consequence reduction of power consumption is not efficient at all. To save power, it is necessary to minimize the power consumption of power-consuming parts and components of the conventional computer motherboard one by one or even bring the power-consuming parts and components to a sleep mode in a program-controllable manner for power saving. However, with the south bridge chip being in control of ACPI and the SIO chip being in control of startup and shutdown, neither the south bridge chip nor the SIO chip can be shut down while in the “suspend to memory” state. Computer motherboards are designed, depending on chipsets for use therewith. Likewise, parts and components of computer motherboards are controlled differently. Hence, it is slow and laborious to develop a computer motherboard whose power-consuming parts and components can be brought to a power-saving mode or a sleep mode one by one, not to mention that a computer motherboard thus developed is intricate, expensive, and incompatible with parts and components of variant design.
U.S. Pat. No. 6,266,776, entitled ACPI Sleep Control, discloses: when the state of an internal battery or an external power supply changes, the change is detected by an embedded controller; the operating system is informed of this change using a power management event signal POWER_PME and an SCI interrupt; and in accordance with the change in power supply state by the internal battery or the external power supply, the current system state changes to another system state. However, U.S. Pat. No. 6,266,776 does not disclose interrupting power supply to a south bridge chip and a SIO chip of a computer motherboard in ACPI S3 so as to save power.
The inventor of the present invention realized the drawbacks of the conventional computer motherboard and endeavored to overcome the drawbacks by inventing a power-saving electronic device for use with a computer motherboard in a “suspend to memory” state.